1. Field of the Invention
The present invention relates to an apparatus and a method for testing a workpiece and, more particularly, to an apparatus and a method for testing electrical characteristics of a semiconductor chip.
2. Description of Related Art
Semiconductor device manufacturing involves many process and testing steps. In general, testing is performed to determine whether the semiconductor device's electrical characteristics conform to its design specifications. Typically, the testing is carried out by contacting pads on the semiconductor devices with one or more testing apparatus.
For example, semiconductor integrated circuits are typically tested in wafer form before they are packaged. Each wafer may undergo a suite of tests immediately after production to separate non-defective wafers from defective ones.
An example of a test apparatus for electrically examining semiconductor integrated circuits (or chips) is disclosed in U.S. Pat. No. 6,118,290. A semiconductor test apparatus typically includes a chuck for supporting a wafer, a performance board and a probe card. The probe card has probe contactors (such as cantilevers or needles) for contacting the contact pads on the chips. The test head is disposed on an upper portion of the test apparatus. The test head and probe card are electrically connected through an interface component comprising the performance board and a pogo module. The performance board, which is mounted on the test head, is a printed circuit board having electric circuit connections unique to a test head's electrical footprint. The pogo module, which includes a large number pogo pins, is disposed between the probe card and the performance board.
FIG. 1A and FIG. 1B are cross-sectional views of a pogo module of a conventional test apparatus. Referring to FIGS. 1A and 1B, pads 922 and 942 of a probe card 920 and a performance board 940, respectively, are electrically interconnected by a pogo pin 962. If the pogo pin 962 extends insufficiently from a pogo module 960 such that contact is not made with a pad 942, as shown in FIG. 1A, or if foreign substances are attached to a portion of the pad 942 such that there is poor contact with the pogo pin 962, as shown in FIG. 1B, then a normal test can not be conducted. In addition, long-term use of the pogo pins leads to increased contact resistance. In the case where only one pogo pin 962 is used, a higher resistance makes it difficult to precisely measure the electrical characteristics of a chip.